The Pyramid of Hellinikon, on the Argolid Plain, looking across to the Argolic Gulf and the Aegean Sea.

Greece, birthplace of the Olympics and mythical home of the gods, is known for its spectacular temples, its exquisite Classical statues, and its jewel-like islands with sandy beaches. But pyramids? That’s Egypt, surely.

Think again. In the eastern Peloponnese of southern Greece are the Pyramids of Argolis. The most impressive – and (relatively speaking) the most famous – of this collection of ancient structures is the Pyramid of Hellinikon. It lies just outside the village of the same name on the Argolid Plain, along an ancient route that leads from Argos, just 10km away, to Tegea (close to modern Trípolis). The region bristles with archaeological evidence of bygone eras, which is not surprising given that Argos, dating back to the Neolithic period, is believed to be the oldest continuously inhabited settlement in Greece. Here heritage enthusiasts are spoiled for choice: two Hellenistic theatres, Roman baths and a nymphaeum, and a medieval castle are among the many sites worth exploring. Though spectacular, none are more mysterious than the enigmatic pyramids just down the road.

Nobody knows when these strange structures were built. They were already old by the time 2nd century BC geographer Pausanias stumbled across them as he journeyed south between the mountains and the sea along the road that led from Tegea to Argos. He kept a record of his travels along a route that took him past the gushing springs of the ancient Erasinos, known today as the Kepfalari River. Today, the modern road negotiates a series of hairpin bends; for Pausanias, the climb was a steady ascent towards Kenchreai – now known as Kechries, but then a thriving port that served Corinth – through a hilly landscape, green with olive groves, apricot orchards, and fragrant lemon trees.

The Pyramid of Hellinikon stands on a low hill protruding from the northern slopes of the valley. From this vantage point, Pausanias enjoyed uninterrupted views across the Argolid Plain to the ancient port of Nafplion and the sparkling blue Aegean Sea beyond. This breathtaking panorama is just as captivating today.

Stone puzzle

Even in Pausanias’ day, the Pyramid of Hellinikon was an enigma. Unlike conventional pyramids, the structure’s base is rectangular rather than square, and the steeply inclined sides are made of different-sized blocks that fit together like a crazy jigsaw puzzle. It is built of locally quarried grey limestone, though its vertical base partly incorporates the rocky outcrop of the hilltop on which it stands. The base has a further anomaly: the south-eastern corner is replaced by a recess that gives access to a narrow passageway which, in turn, leads to a doorway. This is the main entrance to a single chamber with vertical internal walls. The room is about 7m square and, though its walls do not reach full height, it is clear that the ceiling would have been well below the apex of the pyramid.

The entrance to the pyramid in the recessed southeast corner, capped by two converging stones.

There are few historical references to the Pyramid of Hellinikon, perhaps because Greece is spoiled for choice when it comes to archaeology. We have to wait until the first years of the 19th century, some 1,600 years after Pausanias stumbled across it, for another reference, this time by the English antiquarian William Martin Leake, who drew the ruins in 1806 while touring the Peloponnese. And then it took another century before archaeological investigations finally took place. One of the first to explore the remains was Greek archaeologist Apostolos S Arvanitopoulos, who concluded they dated to the Mycenaean Bronze Age, about 1600-1100 BC. However, pottery sherds found in the area belong to the 4th century BC, the height of Greece’s Classical civilisation, and more recent investigations suggest this is the more probable date.

The purpose of this bizarre structure remains a mystery. According to Pausanias, the Pyramid was a burial monument. He writes:

On the way from Argos to Epidauria there is on the right a building made very like a pyramid, and on it in relief are wrought shields of the Argive shape. Here took place a fight for the throne between Proetus and Acrisius; the contest, they say, ended in a draw, and a reconciliation resulted afterwards, as neither could gain a decisive victory. The story is that they and their hosts were armed with shields, which were first used in this battle. For those that fell on either side was built here a common tomb, as they were fellow citizens and kinsmen.

Interestingly, a similar though less well-preserved structure is found at Ligourio. Little of this pyramid remains, its fabric having been robbed for reuse over the centuries – indeed, some its stones may well be found in the walls and foundations of the little local Byzantine church of Agia Marina.

Between the two is a third pyramid: just 15-20 minutes down the road from Hellinikon as you head towards Ligourio, you will pass the tiny ‘blink -and-you’ll-miss-it’ village of Dalamanara, where traces of yet another example of these strange little structures have been found. Remains of a further two pyramids have been identified on the Greek mainland, though very little of either survives: one at Sicyon near Corinth, a town better known for its impressive Temple of Artemis; the other at Viglafia near Neapoli, right on the southeastern tip of the Peloponnese peninsula.

Was Pausanias right? Was Hellinikon a tomb of an early ancestral hero? Or did these pyramids once serve a more prosaic purpose? The clues may lie in the locations of these puzzling little buildings.

The Pyramid of Hellinikon occupies a prime position at the intersection of two major trade routes, while the Ligourio structure sits on the road to Epidaurus on the opposite, eastern, side of the Argolid, at the foot of Mount Arachnaeo. Rather than tombs to fallen heroes, scholars today suggest these were military outposts or blockhouses, strategically placed at critical junctions on important trade routes, with clear views across the surrounding countryside. And, as for their Egyptian-style architecture, could it be that Greek soldiers returning from service in Egypt were impressed by what they saw and decided to mimic the design? Or maybe these pyramids were the work of Egyptian mercenaries serving in Greece, brought over to man these stations and who employed a style of building with which they were familiar.

More controversial still are recent thermoluminescence dating results that tentatively place the Greek pyramids in the early 3rd millennium BC. If correct, this suggests they may even pre-date their famous Egyptian counterparts.

We may never know the secret of the Greek pyramids – and perhaps it is this mystery that fuels their allure.

Most of stone of the pyramid at Ligourio was robbed for reuse in later buildings such as the nearby Byzantine church Agia Marina which stands on the old Mycenaean road from Argos to the harbour at Epidaurus.